Things Things that fucking rule

During the calibration of your display, you will need to choose gamma and white point settings. The correct choice depends on how you are most likely to use your images. The best rule of thumb is this:

Unless you have a color management expert instructing you otherwise, select a 2.2 gamma and a D65 white point.

Because Windows PCs use 2.2 gamma, images edited in the traditional Mac 1.8 gamma will appear incorrectly to most viewers on the Internet—this of course means that your Mac friends need to switch their displays to 2.2 gamma when perusing your 2.2-savvy work.

(Source)